CVE-2026-59886: pyasn1 is a generic ASN.1 library for Python

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HIGH 7.5REMOTEUPGRADE

CVE-2026-59886 is a high-severity flaw (CVSS 7.5) affecting pyasn1. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the univ.Real type converted its mantissa, base, and exponent value to a Python float using exact big-integer exponentiation. A BER, CER, or DER encoded REAL value only a few bytes long can carry a very large exponent, causing float conversion through prettyPrint(), str(), comparison, arithmetic, int(), or an explicit float() call to consume excessive CPU and memory and hang applicatio

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.6% (top 51%)
CISA exploited list	No
Weakness	CWE-400, CWE-770
Published	2026-07-14
Last modified	2026-07-21

Publisher (CNA): GitHub, Inc. · Vendor: pyasn1

Last updated 2026-07-21 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-14 17:17 UTCPublished CVE record published
2026-07-21 14:38 UTCUpdated Record last modified

pyasn1 pyasn1 UPGRADE

Affected: < 0.6.4

Fixed in: 0.6.4

Safe to downgrade to: no unaffected older release

1. Check installed version

pip show pyasn1

2. UPGRADE to 0.6.4

pip install --upgrade "pyasn1>=0.6.4"

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-59886?

pyasn1: upgrade to 0.6.4. Exact commands for each OS are on this page.

Is CVE-2026-59886 being exploited?

CVE-2026-59886 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-59886 affect?

CVE-2026-59886 affects pyasn1. Severity is high (CVSS 7.5). pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the univ.Real type converted its mantissa, base, and exponent value to a Python float using exact big-integer exponentiation. A BER, CER, or DER encoded REAL value only a few byt

How urgent is CVE-2026-59886?

Priority 44/100. High severity; Remotely exploitable, no login, no user action

Software pages

Python vulnerabilities

Related CVEs

CVE-2026-59885 HIGH 7.5 UPGRADE pyasn1 is a generic ASN.1 library for Python
CVE-2026-59884 HIGH 7.5 UPGRADE pyasn1 is a generic ASN.1 library for Python

References

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